AZ31镁合金加工硬化第Ⅲ阶段位错模型

Dislocation Model of the Third Stage Strain Hardening of AZ31 Magnesium Alloy

在温度为200~400℃,应变速率为10^(-4)~10^(-2 )s^(-1)条件下,对挤压态AZ31镁合金进行了拉伸试验,得到了加工硬化率-应力曲线,研究了第Ⅲ阶段加工硬化位错模型以及模型中的硬化参数与软化参数同变形温度和应变速率的关系。结果表明,随着温度升高及应变速率降低,硬化参数减小,硬化速率下降。200~350℃时,软化参数增加,软化速率提高,回复增加。但温度由350℃增加至400℃时,软化参数变化不大,这可能与350℃变形时,镁合金的所有滑移系均已开动,位错湮灭速率达到稳定状态有关。

A tensile test was carried out for the extruded AZ31magnesium alloy along extrusion direction at 200-400℃and strain rate from 10^-4 to 10^-2s^-1,and the strain hardening rate-stress curves were plotted.The dislocation model of the third stage strain hardening and the relationship of the hardening parameter K1and the softening parameter K2in the model between the deforming temperature and strain rate were investigated.The results reveal that K1is decreased with increasing in temperature and decreasing in strain rate,namely the hardening rate decrease.At 200-350℃,the softening rate K2is increased,showing the increase of recovery.However,with temperature increased from 350to 400℃,K2keeps almost constant,which is related to that dislocation annihilation rate has reached a stable state at 350℃because all of the slip systems of the magnesium alloy are in operation at the temperature.